Final answer:
A Pitot tube measures the velocity and pressures such as stagnation and total pressure in flowing fluids but cannot directly measure the discharge rate, which requires additional information about the fluid's cross-sectional area.
Step-by-step explanation:
A Pitot tube is used to measure velocity of flowing fluid and can also be used to measure the fluid's stagnation pressure and total pressure. However, it cannot be used to directly measure the discharge rate since this requires knowledge of the cross-sectional area through which the fluid is flowing, which the pitot tube alone cannot provide. The discharge rate is the volume of fluid passing a point per unit time, often determined by multiplying the velocity by the cross-sectional area of the flow (Q = A x v). Therefore, while pitot tubes can inform calculations of the discharge rate by providing velocity measurements, they cannot directly measure the discharge rate.